Precipitated barium sulfate - How does it function in various coatings?

Precipitated barium sulfate has been widely used as a standard product in various industries: coatings, plastics, rubber, adhesives, inks, etc. The most common one is filled coating to enhance its mechanical performance. Coatings are classified into various types based on the characteristics of their niche markets. How does precipitated barium sulfate work in different coating systems?

1. Used for coatings with high solid content

 For high-solid gloss topcoats, precipitated barium sulfate with a particle size of approximately 0.7-0.8 μm is required. Using a larger particle size will affect the surface gloss. Due to its higher specific surface area, the smaller the particle size, the more substrate is needed. Therefore, a high filling ratio and a high solid content are almost impossible.

Precipitated barium sulfate with a particle size of 0.7μm can prevent flocculation and separation of pigments, thereby reducing the amount of pigments to a very low level. The 0.7 μm precipitated barium sulfate actually has no effect on viscosity within a wide addition range. Therefore, a higher proportion of precipitated barium sulfate can be added in a given formula without affecting the gloss. Therefore, precipitated barium sulfate offers a great opportunity to reduce VOCs and lower formulation costs, as it can replace more expensive pigments.

In addition to white or brightly colored coatings, it is worth mentioning that white precipitated barium sulfate powder can also be used in pure black coatings without affecting the black color. This is because the precipitated barium has a similar refractive index to the commonly used resin, so the precipitated barium sulfate mixed into the system is not white but transparent. Therefore, the carbon black coating will not turn gray. 

Precipitated barium sulfate can also reduce the VOC of the black coating.There are significant differences between carbon black and precipitated barium sulfate in terms of oil absorption rate and specific surface area. Through anti-flocculation, the precipitated barium sulfate can replace a large amount of carbon black, reduce the total amount of the substrate, lower the viscosity, and thereby effectively reduce VOC.

1. Used for powder coatings

Powder coatings are one of the rapidly growing markets in the coatings industry. Due to the special performance of precipitated barium sulfate, its low requirements for substrates and excellent dispersibility, it has become an indispensable component in powder coatings. The specific gravity of precipitated barium sulfate is as high as that of titanium dioxide. So even when using ultrafine powder, there is an opportunity to produce powder coatings without overspraying. In typical powder coating formulations, the mechanical performance of surface treatment are affected by the particle size of precipitated barium sulfate. The smaller the particle size, the better the performance.

1. Used for water-based coatings

Due to its chemical inertness and insolubility, precipitated barium sulfate is as suitable for water-based coatings as traditional coatings. It has been proved that even in electrophoretic coatings (where the requirements for particle deposition or wettability are very complex), micro-powder precipitated barium sulfate can work effectively. The common substitution of precipitated barium sulfate for titanium dioxide is within the range of 10-30%.

1. Used for conductive coatings

Bright conductive coatings are produced using special precipitated barium sulfate of inorganic treatment grade. The electrical conductivity of the coating is provided by inorganic semiconductors, while the other beneficial performance of the precipitated barium sulfate remain unchanged.

Like any other traditional conductive system, a certain fill rate must be reached before the resistivity drops suddenly to form a conductive network. Firstly, the resistivity of the circuit has decreased by several orders of magnitude, while the resistivity of the additional circuit has decreased very little. The permeation point can vary within a wide range of filling ratios, and a loop can be formed through controlled flocculation, while a long time ago, loops were only formed by spreading. Once the solvent is successfully transformed into a thermodynamics unsuitable solvent, the use of organic additives is beneficial.

There is no doubt that conductive coatings can be combined with any other pigments or fillers without losing their conductivity. When the raw material is less than titanium dioxide, the addition of pigment will increase the surface resistivity because the tiny particles stack together to form an additional circuit.

The following is a list of some possible applications and functions of the black conductive coating : 

▪ plastic coating - allow electrostatic spraying 

▪ coil coating - used in cleanroom 

▪ printing ink -used for electronic components encapsulation 

▪ floor coating - to prevent discharge 

▪ PET/PP thin film and foil - get anti-static performance

Ⅴ. Used for automotive coatings

It is well known that precipitated barium sulfate can be used in all coating films of automotive coatings. Just as precipitated barium sulfate can replace some titanium dioxide in electrophoretic coatings, due to its excellent dispersibility and weather resistance, it can also be used in primers and topcoats. The precipitated barium sulfate can stabilize the pigment, prevent flocculation, wear and excessive baking.

Due to the extremely small particle size of ultrafine precipitated barium sulfate, they remain completely transparent even at high filling levels. Therefore, they can be used to increase the solid content of metallic coatings without causing color changes. They can also improve the leveling performance of metal sheets.

Tianlang precipitated barium sulfate

Due to its ultrafine particle size, chemical inertness and good transparency, precipitated barium sulfate has been used by coating manufacturers around the world to fill various coatings, in order to reduce the total material cost and improve mechanical performance. Although it is a national standard product, Tianlang precipitated barium sulfate has a better particle size distribution, higher whiteness and lower oil absorption rate. In addition to the various coatings mentioned above, precipitated barium sulfate can also be used in polymer industries such as plastics, rubber, and friction materials.